This invention relates to magnetometers and more particularly to laser driven helium magnetometers.
Conventional helium magnetometers use a .sup.4 He lamp (a tube containing .sup.4 He gas which is excited by a rf discharge so that it glows) to provide radiation to polarize either the .sup.4 He metastable atoms or ground state .sup.3 He atoms in the cell. The physics of this process is known in the art and described in such publication as:
P. A. Franken and F. D. Colegrove, Physics Review Letters, 1, 317 (1958); PA0 F. D. Colegrove and P. A. Franken Physics Review 119, 680 (1960); and PA0 F. D. Colegrove, L. D. Schearer and G. K. Walters, Physics Review 132, 2561 (1963).
Conventional helium magnetometers use what is referred to as a lamp pumping technique. There are several disadvantages associated with the lamp pumping technique. The lamp radiant intensity is less than optimum for many applications and the lamp radiation contains spectral lines corresponding to the 2.sup.3 S.sub.1 -2.sup.3 P.sub.0, 2.sup.3 S.sub.1 -2.sup.3 P.sub.1, and 2.sup.3 S.sub.1 -2.sup.3 P.sub.2, transitions of .sup.4 He. Radiation of all three transition wavelengths is less effective than radiation of one transitional wavelength. Reference may be made to W. Happer, Review of Modern Physics 44, 169 (1972).